1. Field
An optical lens, light emitting device, and display are disclosed herein.
2. Background
In general, a liquid crystal display (LCD) is a device to convert and transfer various kinds of electric information generated from various devices into visual information using a change in liquid crystal transmittance according to applied voltage. The liquid crystal display needs a halo because it has no magneto-luminescence, but has been widely used because it is low in power consumption, lightweight, and can be constructed of a flat panel type.
The liquid crystal display may include a backlight unit (BLU), which is a light emitting device that provides light to a rear surface of a liquid crystal panel on which an image is displayed because it has no magneto-luminescence. Further, the liquid crystal display may include a color filter substrate and an array substrate, which may be spaced apart from each other at a predetermined interval and opposed to each other, a liquid crystal panel having a liquid crystal layer interposed between the color filter substrate and the array substrate, a backlight unit or backlight to irradiate light to the liquid crystal panel, and other components.
The backlight unit used in the liquid crystal display may be divided into an edge type and a direct type according to positions of light emitting diodes which are light sources. In the case of the edge-type backlight unit, the light emitting diodes are arranged on a side of a light guide plate, and the light guide plate irradiates light, which is irradiated from the light emitting diodes, toward the liquid crystal panel through total reflection.
The direct-type backlight unit uses a diffusion plate instead of the light guide plate. In the case of the direct-type backlight unit, the light emitting diodes are arranged at a rear side of the liquid crystal panel, and thus, irradiate light toward the rear side of the liquid crystal panel.
Uniformity of brightness is an important element to determine quality of the liquid crystal display, and thus, the backlight unit must uniformly irradiate light toward the liquid crystal panel.